1. Field of the Invention
This invention relates generally to light polarization, and more particularly to a method and apparatus for converting non-polarized light into polarized light, where an array of small polarizing cells comprises a flat, molded panel having a reduced thickness and reduced weight and where the panel provides a highly efficient means for polarizing light.
2. Description of the Background Art
Linearly polarized light is light for which the spatial orientation of its electric field lies entirely within one plane. The conventional approach to linearly polarizing light is to use a filter that simply absorbs light of the wrong polarization, passing only light of a chosen linear polarization. This results in linearly polarized light, but at the cost of losing over fifty percent of the incident light available.
Subsequent improvements to polarizing light include use of a beamsplitter and a retarder instead of a filter. See U.S. Pat. No. 5,283,600. In the prior art, a beam of light is directed to a beamsplitter, where light of the desired polarization passes directly through the beamsplitter and out the exit, while the rest of the light (light not of the desired polarization) is reflected 90.degree. to an adjacent mirror. The light is again reflected 90.degree. and passes vertically through a half-wave retarder, which rotates the axis of orientation of the light to the desired polarization. The main disadvantage of this system is size. The size of the beamsplitter must be greater than or equal to the size of the incoming beam of light in order to accommodate and process all of the available light. Further, the exiting light beam is twice the width of the incoming non-polarized light, as light exits through both the beamsplitter and the adjacent retarder. Therefore, the larger the beam of incoming light, such as that used for an overhead projection system, the larger the polarizer must be to accommodate the incoming beam. Such a large size is undesirable for laptop computers and other small-sized component applications.
Further, in prior art systems, a beam of light from a light source is aimed directly upon a polarization converter. Whether the polarization converter is comprised of a single input cell or multiple cells, portions of the light will fall outside of the entrance to the input cell. Because not all of the light is captured and used in the polarization converter, the prior art systems are inherently inefficient.
What is needed is a small, flat, lightweight panel suitable for laptop computers and overhead projectors that comprises a series of narrow, shallow polarizing cells that will polarize all of the incident light in a light beam.